Not Applicable.
The present invention relates to an apparatus for allowing the transfer of bulk materials or fluids in containers, pipes or hoses, in one direction, but not in the opposite direction, and more particularly, to a lighter weight and more efficient swing check valve for use in the transfer of such materials or fluids.
In the trucking industry, dry bulk materials and fluids (i.e., liquids and gasses) must regularly be transferred between truck trailer containers and either fixed storage containers or mobile containers, such as on ships planes or other trucks. In order to facilitate rapid transfer of the bulk materials and fluids, and to limit leakage, swing check valves are typically placed at the inlet ports on the containers. These valves have an internal pivoting gate, referred to as a xe2x80x9cpoppet,xe2x80x9d that swings out of the way when the material flows in one direction, and drops in place to close the valve with a gasket seal when the material attempts to flow in the opposite direction. The valves are self-contained and require no external actuation other than the material flow itself.
Conventional valves for most dry bulk trailer use are typically constructed of aluminum. Although lighter in weight than most metals, aluminum is significantly heavier than many materials, including plastics. In an application such as trucking, where large valves are required and carrying capacities are limited by loaded vehicle weight, any amount of weight reduction in the check valve directly results in greater load capacity, and thereby improved efficiency and reduced costs.
In addition, when a bulk material or fluids (the transferred product) are transferred between storage containers, the transferred product must pass through the valve at a very rapid rate. Any irregularities (including irregularities due to pitting) in the shape of the check valve""s inner surface will create turbulence in the material transfer that can slow the transfer. The greater the extent of the irregularities, the greater the turbulence and the greater the inefficiency in material transfer. Accordingly, it is desirable for the inner surface to be as spherical, smooth and free from pits and protrusions as possible. However, not only are the surfaces of the access port and poppet in a conventional check valve irregular in shape, conventional check valves exhibit burs and pits on the valve""s inner surfaces from the casting process that finishing does not fully remove. These all result in undesirable excess turbulence during material flow.
Furthermore, check valves require regular inspection and maintenance. Each valve has an access port for this purpose, generally located at the top of the valve. Complete inspection can only be accomplished by removing the access port, an external pivot pin assembly for the poppet, and then the internal poppet assembly. The same procedure must be followed to remove the poppet gasket for replacement, the most common maintenance and repair need on check valves. Because the gasket is typically glued to the poppet, the entire poppet assembly often must be replaced when the gasket fails.
The present invention resides in a light weight check valve for use in bulk material transfers, and more particularly for use on truck trailer containers where the reduced weight over conventional metal valves provides efficiency benefits. The check valve is preferably made of an appropriate plastic which can withstand the bulk material or fluid passing through the check valve. Plastic is preferred due to the smooth surface that can be formed, and due to its ability to withstand pitting. Hence, the surface will remain smooth (i.e., will not become severely pitted, which can cause turbulent fluid flow through the valve). However, the check valve can also be made of other light weight materials. The poppet and access port in the present invention are configured such that when the check valve opens to allow air and material flow, the combined interior surfaces of the valve, excluding the inlet and outlet flow ports, mate smoothly against one another to form a nearly spherical shape. This, in combination with the smooth surface of the valve, reduces the amount of turbulence in the valve, increases flow efficiencies and enables increased flow rates.
Further, the poppet assembly and access port are coupled internally so that both can be removed as a single unit for easy and rapid inspection of the entire valve. A simple seal such as an O-ring, or preferably a Quad-Ring(copyright) (available from Minnesota Rubber of Minneapolis, Minn.), located on the rim inside the valve against which the poppet closes, forms the poppet seal. In contrast to conventional check valves, this Quad-ring seal can be easily and rapidly replaced when necessary.
The present invention is readily adaptable to virtually any size check valve, and can readily be combined with numerous interfaces for connection to a variety of containers, pipes and hoses.
Additional features of the present invention will be in part apparent and in part pointed out hereinafter.